CVE-2021-43633: Sourcecodester Messaging Web Application 1.0 is vulnerable to stored XSS

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-43633 is a medium-severity flaw (CVSS 5.4) affecting messaging web application. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Sourcecodester Messaging Web Application 1.0 is vulnerable to stored XSS. If a sender inserts valid scripts into the chat, the script will be executed on the receiver chat.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-04-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: messaging web application project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-04-14 13:15 UTCPublished CVE record published
2026-06-17 04:11 UTCUpdated Record last modified

messaging web application project messaging web application DOWNGRADE

Affected: 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

apt-cache policy messaging-web-application || rpm -q messaging-web-application || messaging-web-application --version

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison messaging-web-application sudo apt install messaging-web-application=<VERSION_BEFORE_1.0> sudo apt-mark hold messaging-web-application

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list messaging-web-application sudo dnf downgrade messaging-web-application-<VERSION_BEFORE_1.0> sudo dnf versionlock add messaging-web-application

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-43633?

messaging web application: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-43633 being exploited?

CVE-2021-43633 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-43633 affect?

CVE-2021-43633 affects messaging web application. Severity is medium (CVSS 5.4). Sourcecodester Messaging Web Application 1.0 is vulnerable to stored XSS. If a sender inserts valid scripts into the chat, the script will be executed on the receiver chat.

How urgent is CVE-2021-43633?

Priority 31/100. No elevated risk signals yet.

References

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